The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In automatic transmission field, technologies for achieving more shift stages to improve fuel consumption and driving efficiency have been developed.
In this sense, research on an engine has been undertaken to achieve weight reduction and to enhance fuel consumption by so-called downsizing, and research on an automatic transmission has been simultaneously performed to provide better drivability and fuel consumption by achieving more shift stages.
In order to achieve more shift stages for an automatic transmission, the number of parts, particularly the number of planetary gear sets is typically increased. This negatively affects installability, production cost, weight, and power flow efficiency.
Therefore, enhancing fuel efficiency of an automatic transmission with reduced parts becomes an important factor.
In this respect, an eight-speed automatic transmission having a planetary gear train has been recently introduced.
However, we have discovered that the total length of the eight speed automatic transmissions is lengthy due to arrangement of multiple planetary gear sets, therefor undermining installability of the transmission.